Making things a little less shaky / PG&E pipeline in delta offers insurance against disaster for company, customers

PG&E installing a natural gas pipeline in case the main pipeline breaks in a catastrophe. PG&E / Courtesy to The Chronicle MANDATORY CREDIT FOR PHOTOG AND SAN FRANCISCO CHRONICLE/NO SALES-MAGS OUT

PG&E installing a natural gas pipeline in case the main pipeline breaks in a catastrophe. PG&E / Courtesy to The Chronicle MANDATORY CREDIT FOR PHOTOG AND SAN FRANCISCO CHRONICLE/NO SALES-MAGS OUT

Photo: PG&E

Photo: PG&E

Image
1of/1

Caption

Close

Image 1 of 1

PG&E installing a natural gas pipeline in case the main pipeline breaks in a catastrophe. PG&E / Courtesy to The Chronicle MANDATORY CREDIT FOR PHOTOG AND SAN FRANCISCO CHRONICLE/NO SALES-MAGS OUT

PG&E installing a natural gas pipeline in case the main pipeline breaks in a catastrophe. PG&E / Courtesy to The Chronicle MANDATORY CREDIT FOR PHOTOG AND SAN FRANCISCO CHRONICLE/NO SALES-MAGS OUT

Photo: PG&E

Making things a little less shaky / PG&E pipeline in delta offers insurance against disaster for company, customers

1 / 1

Back to Gallery

2007-06-23 04:00:00 PDT McDonald Island, San Joaquin County -- On this crop-covered island in the sweltering delta, Pacific Gas and Electric Co. is building a $56.9 million insurance policy.

The utility is stringing a second pipeline beneath the cornfields and river channels to make sure that a disaster won't cut it off from its main natural gas storage facility.

McDonald Island sits atop an underground reservoir packed with enough fuel to supply all PG&E customers for more than one month. Right now, only one pipeline connects the reservoir to the outside world. If it breaks in an earthquake or flood, the gas would be trapped. Buying replacement gas could cost up to $1 billion.

So on Friday, work crews slowly fed a 24-inch-wide steel tube into a hole in the black dirt. The new pipeline will dive 100 feet underground to pass beneath the Empire Cut river channel nearby, then emerge on another island to the south.

That far down, it should be able to withstand a magnitude-9 earthquake, according to PG&E. It also follows a different path than the existing pipeline, minimizing the chances that both would be damaged at the same time.

"We're burying the line deeper, getting it out of harm's way, and we're taking a different route," said Robert Howard, the utility's vice president for gas transmission and distribution. "This gives us significant reliability."

Disaster here is a real possibility.

These islands once were a vast marsh. Draining them to plant crops caused the land to subside, and now the fields lie well below sea level, protected from the surrounding river channels by levees.

Three years ago, a levee breach flooded Lower Jones Tract, one of the islands along the new pipeline's route. Eight homes, seven labor camps and several barns were destroyed there and on neighboring Upper Jones Tract.

McDonald Island flooded in 1982. PG&E's facilities there, however, are raised above the surrounding cropland and sit above sea level, so they can't easily be swamped.

"Even after the flood, we continued to move gas off the island," said Curtis Tonetti, PG&E's gas maintenance supervisor for McDonald Island. "We kept working. We just went from platform to platform by boat."

Although the company has other places to store natural gas, this reservoir is the largest. Buried 5,200 deep and capped by layers of shale and clay, the reservoir's porous rock holds gas that the company buys in the summer when prices are relatively low and then injects underground. Come winter, the gas is fed into PG&E's 6,136 miles of transmission pipelines to serve the utility's 4.2 million natural gas customers.

Money for the project will come from the utility bills of PG&E's customers. The company plans to spend about $2.8 billion this year maintaining and expanding its networks of power lines and stations, and natural gas pipes.